Accomplishing the yarn feed through a thread regulator by mechanical means with the aid of a preferably flexible needle-shaped element is already known. Accomplishing the threading process by means of ejectors/nozzles in parts of the yarn feed path which extends through various elements in the yarn feed system, is also known. Thus a nozzle or ejector arrangement in the actual thread regulator, by means of which the end of the yarn is introduced via an intake aperture, and the nozzles or ejectors are thereafter acted upon in order to obtain the threading function, is also known.
Making use of the intake thread brake (in relation to the thread regulator) in the yarn feed path and locating the intake brake in connection with the thread regulator is also known. In the known arrangements, a number of transducers are often used which are intended to indicate the positions (presence) of the yarn on its path through the particular elements in the yarn feed system. So-called controlled brakes on the intake side of a thread regulator are also already known. Brakes of this type facilitate variations in the yarn brake parameters and the brake in question often works on the "on-off" principle.
One requirement is to be able to achieve an effective threading function which, for the major part at least, runs automatically. The threading function is therefore to be capable of including yarn control function(s) at the exit from the thread regulator, so that further feeding can be accomplished through any subsequent exit thread brake as far as the textile machine using the thread, especially a loom.
There is also a requirement that the yarn delivery system should be capable of containing as few components as possible and one objective expressly stipulated in certain contexts is that the number of transducers/sensors for detecting the presence (positions) of the yarn should be as small as possible.
A simple and unambiguous handling of the yarn threading function is desirable, particularly in view of the fact that malfunctions can occur when the textile machine/loom is operating, especially breaking of the yarn. One ob3ect of this invention, therefore, is to achieve an entirely automatic threading process, or at least one which is automatic in many sections. Having a yarn cleaning process forwards and/or backwards on the thread path prior to the threading process should achieve the simplified handling and construction desired. Achieving such threading and yarn cleaning processes is a complex technical problem to which the present invention affords a solution.
One problem in devising an effective threading function in a yarn path of this type is obtaining an efficient transfer of the yarn between the intake thread brake and the thread regulator. Normally there is a relatively large gap between the said brake and the thread regulator. The invention takes account of those cases in which the intake thread brake is located closer to the thread regulator. In such cases it is a question of achieving an appropriate thread-bearing and thread delivering medium flow in which the end of the yarn and following parts of the yarn can be connected to the thread regulator's intake (inlet). In any opening of a medium passage for supporting and delivering the yarn/end of the yarn, there are problems in preventing the end of the yarn from shifting to the side and leaving the predetermined direction. The present invention is directed towards solving even this problem.
In what can essentially be regarded as the main characteristic of a device according to the invention, among other things, the intake brake is connected to the rear section of the thread regulator and, by using one or more ejectors, a production medium flow is developed on the end of the yarn/the yarn which, on applying/presenting/positioning the free end of the yarn against the intake brake aperture, causes it to be fed in through the said aperture, carried through the intake brake and introduced into the first duct in the thread regulator through its intake orifice. The strand of yarn can thereby be carried through the parts of the intake brake serving for actual braking, or in an initial phase past these, before then undergoing in a subsequent phase a simple stretching or suitable lateral adjustment as it is led in from the side into the active parts of the brake. The intake thread brake may be assigned one or more ejectors of its own and/or utilize one or more ejectors in or on the thread regulator's first and second ducts. The ejector(s) is/are controlled by connected control unit(s) and, depending on its controls, give rise to an initial medium pressure at the orifice of the first duct facing onto the intake thread brake which is lower than a second medium pressure at or behind the said aperture on the intake thread brake for development of the production medium flow.
In one embodiment of the object of the invention, the intake thread brake includes a controllable brake element, by means of which the braking force acting on the yarn can be varied and/or applied and relaxed. When applying (positioning) the end of the yarn to the intake thread brake, the brake element is deactivated by means of an appropriate control unit or a manually operated mechanical operating device, and remains entirely or partially (temporarily) deactivated during any threading process. In a preferred embodiment, the intake thread brake and the thread regulator are controlled when in operation (weaving), whereas during the threading process the intake thread brake can be separately controlled. The relevant controls are achieved by means of one or more of the said units.
In one embodiment, control of the yarn within the intake thread brake and thread regulator is coordinated with control of the yarn before the brake and after the thread regulator. Consequently in this case there is a preferably automatic element, which carries any free yarn end to the insertion position in front of the intake thread brake aperture. Thereupon (or an instant before) the said ejector/ejectors in the brake and thread regulator is/are actuated for feeding the yarn through into these units. On the thread regulator's exit side there are other automatic elements which take up the ejected end of the yarn and carry this on to any subsequent outlet brake and the textile machine.
One or more control units control the first and second elements and the entire threading process is thus fully automated.
In one embodiment, propulsion along a first and second thread feeding line is proposed. An initial thread feed resistance may thereby be present in the first line, and the second line presents curves through which the end of the yarn must pass. The rate of yarn feed may therefore exceed the maximum rate which the end of the yarn should have when passing through any curves. During such passage the thread's rate of advance when threading would thus have to be reduced, at least temporarily. In the first case this is brought about by activating the brake element in the intake thread brake, which activation is effected by a control unit. In the second case the impelling medium flow is influenced by controlling the ejectors (the supply of impelling medium to the ejectors). Pulsating impelling medium for the yarn are thereby conceivable.
In a preferred embodiment, the intake thread brake is assembled together with the thread regulator on the latter's rear section (end), in such a way that the yarn path in the brake lies essentially in line with the intake opening of the first duct. The intake thread brake can thereby be fitted with a shell section which essentially encloses the brake element and the thread feed path tightly, so that a sealed common chamber exists enclosing the said chamber and the first and second ducts. In another embodiment, the brake element is open to the surrounding atmosphere, affording easy manual access for the removal of dust, carrying out servicing etc.
A special control function is available on the version with an essentially sealed inner chamber in the intake thread brake. Advance suction of air in the common chamber is to be performed with the ejector function(s) in order to produce stable flow conditions in the yarn path before the actual threading function is commenced, thereby eliminating the spontaneous oscillation phenomenon in any remaining air.
A process according to the invention involves the phase in the respective threading cases, in which the free end of the yarn is applied to the inlet aperture of the intake thread brake, the yarn end in the case of threading after yarn fracture being applied to the aperture after the yarn cleaning facility of the respective element before and/or after the intake yarn brake or thread regulator has been operated or actuated for cleaning the yarn behind or ahead of the remaining/existing yarn in the intake thread brake and/or in the thread regulator. Further phases in the process involve the actuation of the ejector(s) applied in the intake yarn brake and/or one or more of the said ejectors on or in the first and second ducts by means of the application of medium pressure source(s) together with the development of a yarn producing medium flow generated by the ejector/ejectors and drawing the end of the yarn in through the aperture in the intake thread brake, through the brake and into the first duct.
In further developments of the new process according to the invention the automatically functioning yarn-applying element is influenced/controlled in such a way that the end of the yarn is automatically carried towards the brake's intake aperture. On leaving the thread regulator, the automatic catcher is induced to catch the end of the yarn and to guide this towards the textile machine, in particular the loom, via any controlled or uncontrolled exit thread brake positioned after the thread regulator.
The automatic threading processes are controlled by one or more units for controlling the yarn feed system and/or the textile machine.
The construction described above provides effective threading functions which can be performed fully automatically and which can, moreover, function with preparatory cleaning processes, preferably automatic ones, prior to the respective threading process. Even complex threading paths can be incorporated in connection with the thread regulator and intake brake. Acceleration and retardation of the yarn during the respective on threading process can be achieved by controlling the conveying medium flow, which opens up the possibility for technically simply constructed solutions for yarn feed on threading. The equipment can be controlled from the control unit(s) of the thread regulator(s) and intake brake(s) and/or the textile machine, in particular the loom. A transducer can be used to indicate the carrying out of threading, yarn breaks, etc. In one embodiment, the end of the yarn can be furnished with an applicable element, which is to some extent coordinated with the respective duct wall as the yarn is delivered. This element, for example a spherical one having a certain flexibility, is positioned so as to cause a relatively large pressure differential in front of or behind the end of the yarn fitted with the said element, thereby assisting appropriate propulsion of the yarn in the respective duct. The ball/element can be automatically removed, for example cut off, by means of a removing/cropping element at a suitably predetermined point along the yarn path. An air suction effect may be provided in the ducts in the brake and thread regulator/winding pipe by means of an ejector on the exit aperture of the winding pipe, on the exit eye, etc. A static air flow can exist and (a) dynamic air flow(s) may be temporarily applied. The medium pressure will be lowest in front of the leading yarn end. Threading of two or more "parallel yarns" (running parallel side by side) may be performed with the proposed equipment. In the same way the parallel yarn tracks can also be led through the same intake thread brake or alternatively via each's own brake.